DESCRIPTION: (Applicant's Abstract) Procedures will be developed to test the effects of drugs on monkey visual and auditory list-memory. The list-memory procedures are identical to ones used to test human list memory. Groups of monkeys will receive either lists of "travel slides" or environmental sounds, followed by a single test item. They then respond as to whether the test was or was not in the list. Retention delays test memory. Preliminary results show that visual and auditory memory are each composed of separate memory systems--systems that produce primacy effects (good memory for first list items, thought to be related to long-term memory) and recency effects (good memory for last list items, thought to be related to short-term memory). Auditory and visual memory are very different in these processes, and limits the possible mechanisms accounting for memory. The proposed experiments will specify these different memory mechanisms by manipulating-retention interval, stimulus presentation time, interstimulus interval, item repetition, items added to the beginning or end of auditory and visual memory lists, and proactive and retroactive interference processes. Understanding how memory works and the mechanisms of drugs and drug abuse on memory is necessary for any effective treatment regime.